N=int(input())
C=list(input())
rednum=C.count('R')
rednumleft=0
for i in range(rednum):
    if C[i]=='R':
        rednumleft+=1
print(rednum-rednumleft) N=int(input()) N int(input()) int input() input C=list(input()) C list(input()) list input() input rednum=C.count('R') rednum C.count('R') C.count C count 'R' rednumleft=0 rednumleft 0 for i in range(rednum):
    if C[i]=='R':
        rednumleft+=1 i range(rednum) range rednum if C[i]=='R':
        rednumleft+=1 C[i]=='R' C[i] C i 'R' rednumleft+=1 rednumleft 1 print(rednum-rednumleft) print rednum-rednumleft rednum rednumleft rednum=C.count('R') C.count('R') rednum C=list(input()) list(input()) C rednumleft=0 0 rednumleft N=int(input()) int(input()) N rednumleft+=1 1 rednumleft
N=int(input())
C=list(input())
rednum=C.count('R')
rednumleft=0
for i in range(rednum):
    if C[i]=='R':
        rednumleft+=1
print(rednum-rednumleft)